Automatic override for engine safety shutdown systems

ABSTRACT

A solid-state electronic device which senses stator voltage during normal restart of an internal combustion engine following intentional shutdown of during attempted restart of an engine following shutdown thereof by a system detecting abnormal engine operating conditions, and which overrides the shutdown system to permit at least temporary engine operation during a predetermined interval in which abnormal operating conditions may persist. The override device includes a reactive charging and discharging timing stage which determines the override period by a controlled discharge commencing when starter operation ends, as well as amplification and switching stages which actuate an enginecontrolling component to both initiate and end the override period in response to the operation of the reactive timing stage.

United States Patent Paul a. ram.-

[72] Inventor LeRoy, Mich. [211 Appl. No. 852,354 [22] Filed Aug. 22, 1969 [45] Patented M1531, 1971 [73] Assignee Kysor Industrial Corporation Cadillac. Mich.

[541 AUTOMATIC OVERRIDE FOR ENGINE SAFETY SHUTDOWN SYSTEMS 9 Claims, 2 Drawing Figs.

[52] US. Cl. 123/179, 123/196, 123/198, 290/37, 290/38 51 In, (L ...F02n 11/08, F02n 1 1/ 10, F021) 77/08, 184 6 D [50] Fleldotsenrch 123/198, 198 D, 41.15.1465 C, 179, 196; 290/37, 38; 184/6 D [56] References Cited UNITEDSTATES PATENTS 2,122,049 6/1938 Stark 123/196 S 2,499,319 2/l950 Lillquist 123/198 D X 2,924,209 2/1960 Schott 123/198 D X 3,116,729 H1964 Crowe 123/179 3,362,388 1/1968 Lindberg, et al l23/l46.5 C 3,385,278 5/1968 JohnsonJr et a1. 'l23/4l.l5 X 3,415,999 12/1968 Noury 290/38 3,514,621 5/1970 Farmer et al. 290/37 Primary Examiner-Al Lawrence Smith Attorney-Price, Heneveld, Huizenga & Cooper engine operation during a predetermined interval in which abnormal operating conditions may persist. The override device includes a reactive charging and discharging timing stage which determines the override period by a controlled discharge commencing when starter operation ends, as well as amplification and switching stages which actuate an enginecontrolling component to both initiate and end the override period in response to the operation of the reactive timing stage.

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AUTOMATIC OVERRIDE FOR ENGINE SAFETY I l SHUTDOWN. SYSTEMS BACKGROUND in the past, automated engine shutdown systems or motor vehicles and the like and particularly for trucks, have been devised which automatically shut down the operation of the engine whenever an abnormal operating condition is detected, such as dangerously low engine oil pressure or dangerously high engine or engine coolant temperature. Such systems are steadily finding increased usage, since they can prevent serious damage to or even total loss; of an expensive engine which would otherwise surely occur if? the driver failed to note the presence of the abnormalcondition-from his instruments, or if the instruments weredefective orgave inaccurate readings.

Such shutdown systems are not a. complete answer to the problem in andofthemselves, however, since they may cause shutdown at any time, withorwithout advance warning, and manysuch times it may be quite important or even essential-to allow at least limited@additional:engineoperation, as for example to provide for the safety of the vehicle or of its driver. This is particularly soif, for example, the vehicle is equippedwith power-operated steering or brakes andshutdown occurs at highway speeds, or while descending hills, while traveling a sharply curving roadway, orwhenmovement to a safe parking place is required. (Consequently, all successful shutdown systems of this general character must have some type ofoverride system which-will permitrestartingof'the engine and at least brief subsequent operation.

in the past, override systems for-this purposehave been provided in the form of manually. operated switches orthe like which the driver must operate prior'to or at the-same time as restartingis attempted. Becauseanysuch system of this type has limitations which are clearlyapparent from the standpoint of operator inconvenience, other-types of overrides have been; proposed which'iwill operate ima-more automatedmanner, and which will permit restartingsin more customarily manner, following which shutdown is once again allowed to occur after a predetermined interval of operation. Overridesystems such as these are eminently more desirableand, considered from apurely functionalpoint of view, are satisfactory. However, actual override devices of this type which have heretofore been provided have generally been-characterized by thepresence-of numerous purely mechanical components, timer motors, heavy moving-contact switches, and/or electrical circuits which produce a significant current drain on the engine ignition or generating circuits, as well as by the-presence-of heating elements and temperature-responsive switches operated in conjunction therewith. Therefore, such previous override systems have been expensiveto'manufacture and purchase,

difiicult to mount or operate dueto their relative size, weight A and position requirements, and have required considerable repair and maintenance. Also, inmany instances, the reliability has not been of a desirably highlevel.

SUMMARY OF THEIN-VENTION The present invention has as a major objective the provision of a new form of override system which is of a purely electronic nature, which-is comprised substantially entirely of solid-state components, and which is therefore extremely reliable, not subject to maintenance -or upkeep problems, of a all apd compact physical nature and which has novel Briefly stated, the override system of the invention com prises an input terminal which is connected to the starterenergizing circuit of the vehicle and which couples voltage from the starter circuit to a reactive timing circuit to charge the latter. The timing circuit commences a timed discharge,- when starter-operation is terminated, and a multistage voltage amplification and switching circuit coupled to the timing circuit receives the charging and discharging voltage present at the latter. Thecharging voltage immediately triggers the multistage circuit such that the shutdown system is immediately overridden, and the multistage circuit is again triggered after a predetermined interval at a particular discharge level of the timing circuit. At this point, the shutdown system is no longer overridden, and thus will cause secondary shutdown a predetermined interval after restart has occurred. The override device of the invention is therefore completely automatic in operation, and requires no specific actuation by the vehicle operator; furthermore, successive restarts can be initiated at will, and each will be allowed to continue for a similar time interval, following which automatic shutdown once again occurs.

IN THE DRAWINGS I PREFERRED EMBODIMENT The automatic override system 10 of the invention, illustrated in detail'in the schematic of FIG. 1, is shown connected into an exemplary preferred shutdown system 20 in FlG. 2. Referring first to'the latter figure for a general understanding of the complete shutdown system, it will be seen that the storage battery 22 of the vehicle has its positive terminal (for the particular polarity arrangementof both FIGS. 1' and 2) connected to a terminal B of a typical automotive ignition switch 24, from which electrical power from the battery is supplied to other vehicle circuits, including the ignition circuit (from a terminal'l), an accessory circuit (from a terminal A) and the starter circuit (from a terminal s). As willbe' understood, the ignition switch 24 is'typicalof'many such components presently in use in which the starter circuit is auto matically energized by movement to a particular position'of the ignition key, as is the ignition circuit. There are, of *course,

'othersimilar ignition switcher'which' are presently known and in use, with'the electrical connections which are directly analogous to those illustrated. These include, for example,

switches of the same basic type, but in which the starter circuit is manually energized through a push button start switch.

The shutdown system 20 of FIG. 2 illustrates the use'of one particular exemplary engine-controlling component '26 and comprising a solenoid-operated fuel valve, another'such example of component comprising, for example, a solenoid 'air valve. As will be understood, engine control components of the type illustrated at 26permit engine operation or provide" engine shutdown'by controlling the fuel supply; in the case of the fuel valve 26, there is a direct shutoff of fuel upon'actua-" tion of the valve, whereas in the case of air valve of the type mentioned above the fuel supply is controlled by a pneumatic power cylinder (not shown) whose actuating air is controlled by a valveiWhile engine control is thus shown to beaccornplished through controlling the fuel supply, it should of course be understood that engine control can also be accomplished in a directly analogous manner by opening or closingthe ignition circuit through an appropriate switch.

In the overall system 20, power from the battery is supplied through the ignition switch 24, from both the ignition circuit terminal I and the starter circuit terminal S, along conductors 30 and 32', respectively. Conductor 30 is connected to terminal 1 of the override system 10 of the invention, as well as to a common contact of a temperature sensor component 34' to the engine control component 26,'to terminal 4 of the autoabove to produce an immediate switched output at terminal 3 of the override device, thereby energizing the engine-control component and permitting starting of the engine. The same is true during all normal starting since at such time there will be little or no engine oil pressure (none until the engine is at leas cranked by the starter, and then. very little until it actually 7 starts) and the pressure sensor 42 will therefore not pass current from the ignition circuit to the engine control component to energize the latter. Furthermore, engine temperatures may rise drastically during a brief shutdown after hard running, and at such a time the temperature sensor 34 may also open the circuit to the engine-control component. Thus, even normal starting is accomplished through the operation of the present override device,'which overcomes the shutdown condition duct. At this point in time, the main switching transistor Q1 is also immediately and sharply shut off, thereby removing the excitation voltage from conductor 45 and from the enginecontrol component 26 to cause engine shutdown if either of the sensors 34 or 42 continues to detect an abnormal engine operating condition. or course, in the event that during this brief timed interval of allowable restart operation (which may be on the order of thirty seconds), an abnormal engine operating condition previously. detected is no longer present, or in the event of a normal start following a normal or intentional shutdown, the sensors 34 and 42 will operate in a normal manner and will maintain the excitation of the engine control component, through conductors 30, 46, 44 and 45; consequently, under these circumstances the cutofi of transistor Q1 will have no effect, and the engine will maintain operation. The operator of the vehicle will be aware of a-return ofnormal engine operating conditions, however, since the warning light or alarm bell 38, 40 will cease operation.

It is to be noted that with the present invention the allowable-period of restart engine operation is independent of the length of time it may actually take to restart the engine, since the timing interval does not commence until starter operation ends, i.e., at the instant the engine starts and the starting circuit is deenergized. Any desired number of similar restart operations may be initiated at the discretion of the operator, simply by attempting to start the engine in the normal manner each time it isautomatically shut down by the system. Also, there is no significant current drain on the vehicle power system caused by the present override, and thus normal engine ignition and normal starter excitation will 'both be present. Many other advantages are also provided, including the fact that the override circuit or system forms an extremely compact package which can be mounted in a vehicle in any position, which is an advantage not provided by prior systems of a predominantly mechanical nature. Also, the override requires no resetting actuation and requires no delay between successive restart operations.

It is entirely conceivable that upon examining the foregoing disclosure, those skilled in the art may devise particular embodiments of theconcepts forming the basis of the invention which differ somewhatfrom the preferred embodiment shown and described herein, or may make various changes in structural details to the present embodiment. In this connection, it is to be noted that other parts of the vehicle may if desired by mounted by appropriate sensors connected into the overall shutdown system; for example, engine coolant pressure may be so monitored, as may transmission or engine lubricant temperature. Similarly, other specific types of sensors or other components may be utilized. Consequently, it is to be recognized thatthe preferred embodiment shown and described is for purposes 0 general illustration only and is in no way intended to illustrate all possible fonns of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. An electronic override device for engine safety shutdown systems, comprising: means for monitoring engine operation and providing an electrical input signal condition in response to the restarting of a shutdown vehicle engine; a timer means for receiving said input signal and providing an electrical control signal having a progressive time-dependent variation after receipt of said input signal; and an electrical driver and switching circuit means for initially providing a first electrical output switching function and for receiving said control signal and providing a second electrical output switching function following the occurrence of a predetermined level condition of said control signal; said driver and switching circuit means being connectable to an engine-control component to override control of the engine by such shutdown system by coupling said first and second output switching functions to said component to thereby control the same.

2. The override device of claim 1, wherein said means for monitoring provides a first electrical input signal condition during attempted engine restart and a second such signal condition upon termination of such attempt, and wherein said timer means provides said control signal variation only after receiving said second signal condition.

3. The override device of claim 1, wherein said'timer means comprises a reactive charging and discharging circuit.

4. The override device of claim 1, wherein said driver and switching means comprises at least a level-detecting stage and a switching stage coupled thereto and controlled thereby.

5. The override device of claim 4, wherein said driver and switching means comprises at least one amplification stage.

6. The override device of claim 4, wherein said timer means comprises a reactive charging and discharging circuit.

7. The override device of claim 2, wherein said first input signal condition comprises the presence of an electrical voltage and said second such condition comprises the absence of such voltage,'and wherein said timer means comprises a reactive circuit which is charged by said voltage and which discharges upon the absence thereof.

8. The override device of claim 7, wherein said driver and switching means comprises a multistage solid-state circuit having at least a level-detecting stage and a switching stage coupled thereto and controlled thereby.

9. A safety shutdown system for motor vehicle engines and the like, comprising in combination: a control component connected to a part of the engine to shut down operation of the engine upon receiving a predetermined shutdown signal condition and to permit engine operation upon receiving a different signal condition; at least one sensor means connected to the engine and coupled to said control component, for detecting a predetermined abnormal condition of engine operation and initiating such shutdown signal condition; an override means coupled to said control component for providing said different signal condition thereto for a predetermined time interval to permit engine operation during such interval despite such abnormal condition of operation; said override means including means for monitoring engine operation and providing an electrical input signal condition in response to the restarting of a shutdown engine, 'a timer means for receiving said input signal and providing an electrical control signal having a progressive time-dependent variation after receipt of said input signal, and an electrical driver and switching circuit means for receiving said control signal and providing an electrical output switching function prior to the occurrence of a predetermined level condition of said control signal, said driver and switching circuit means being connected to said control component to effect override thereofby coupling said output switching function thereto, such switching condition comprising said different signal condition. 

1. An electronic override device for engine safety shutdown systems, comprising: means for monitoring engine operation and providing an electrical input signal condition in response to the restarting of a shutdown vehicle engine; a timer means for receiving said input signal and providing an electrical control signal having a progressive time-dependent variation after receipt of said input signal; and an electrical driver and switching circuit means for initially providing a first electrical output switching function and for receiving said control signal and providing a second electrical output switching function following the occurrence of a predetermined level condition of said control signal; said driver and switching circuit means being connectable to an engine-control component to override control of the engine bY such shutdown system by coupling said first and second output switching functions to said component to thereby control the same.
 2. The override device of claim 1, wherein said means for monitoring provides a first electrical input signal condition during attempted engine restart and a second such signal condition upon termination of such attempt, and wherein said timer means provides said control signal variation only after receiving said second signal condition.
 3. The override device of claim 1, wherein said timer means comprises a reactive charging and discharging circuit.
 4. The override device of claim 1, wherein said driver and switching means comprises at least a level-detecting stage and a switching stage coupled thereto and controlled thereby.
 5. The override device of claim 4, wherein said driver and switching means comprises at least one amplification stage.
 6. The override device of claim 4, wherein said timer means comprises a reactive charging and discharging circuit.
 7. The override device of claim 2, wherein said first input signal condition comprises the presence of an electrical voltage and said second such condition comprises the absence of such voltage, and wherein said timer means comprises a reactive circuit which is charged by said voltage and which discharges upon the absence thereof.
 8. The override device of claim 7, wherein said driver and switching means comprises a multistage solid-state circuit having at least a level-detecting stage and a switching stage coupled thereto and controlled thereby.
 9. A safety shutdown system for motor vehicle engines and the like, comprising in combination: a control component connected to a part of the engine to shut down operation of the engine upon receiving a predetermined shutdown signal condition and to permit engine operation upon receiving a different signal condition; at least one sensor means connected to the engine and coupled to said control component, for detecting a predetermined abnormal condition of engine operation and initiating such shutdown signal condition; an override means coupled to said control component for providing said different signal condition thereto for a predetermined time interval to permit engine operation during such interval despite such abnormal condition of operation; said override means including means for monitoring engine operation and providing an electrical input signal condition in response to the restarting of a shutdown engine, a timer means for receiving said input signal and providing an electrical control signal having a progressive time-dependent variation after receipt of said input signal, and an electrical driver and switching circuit means for receiving said control signal and providing an electrical output switching function prior to the occurrence of a predetermined level condition of said control signal, said driver and switching circuit means being connected to said control component to effect override thereof by coupling said output switching function thereto, such switching condition comprising said different signal condition. 